I get so tired of reading "transition words" that I am always trying to help my students develop more fluent transitional ideas. I tell them to develop a transitional sentence for each paragraph that unites it with the overall theme or message of the work. Focus on keeping it interesting, and less on using a formulaic word.
In addition to transitions from one sentence to the next, there need to be transitions from one paragraph to the next. Generally, these transitions are necessary from one body paragraph to the next.
There is a kind of trick you can use until transitions come more naturally to you, as you gain skills as a writer. At the end of a body paragraph, you need to write a sentence that includes the topic of the body paragraph you are in and that also includes a mention of the topic of the next paragraph. So, for example, if you are moving from a body paragraph about diet to a paragraph about sedentary lifestyle, you might finish the former with a sentence like this:
Not only does our fast food diet contribute to obesity, but also our sedentary lifestyles.
You can see that a mention of the old topic and the new topic creates a bridge for the reader to cross, from one idea to the next. As you move from one body paragraph to the next, try this trick. Eventually, forming this bridge will come easily to you.
When writing, it is important to vary your sentence structure. The way I began this first sentence is an example. You should vary sentence structure from complex to simple sentences. Next, you should use words or phrases that create smooth transitions. Much like the sentence I just used.
To write effectively, you must include words such as:
next, then again, perhaps, for example, finally, later, meanwhile, while, suddenly, likewise, in the same way, however, therefore, for this reason, on the other hand, even though, also, additionally, as a result, lastly, moreover, for instance, in other words, truly, in fact, although, still, even though, etc.
Begin each paragraph with one of the above mentioned transitions. To keep the writing flowing, continue to use transitions throughout the writing.
These are just a few examples. For more examples, see the websites below.